Microphone Not Working in Steam?

Hi all, i have recently purchased a headset with microphone complete to play my steam games, mostly Team Fortress 2.
I put the microphone cables in the correct ports and i can hear the music etc but cannot hear or detect the microphone on the headset, also I launched a game and when use the microphone while playing a game people can't hear me. I say "hey, can anyone hear me?" and I get no answer.
The microphone is working. How do I solve this?

I have been using my ps3 eye as my microphone in win7, and it was working great for 3 days in CS:Source, then randomly in the middle of a game it stopped working. It no longer works in steam, my other mics work, and the ps3 eye mic works in ALL other games just not steam. Works on desktop and audio device setting as well, I didn't change anything, it literally just stopped working in steam. I tried allow access to programs etc, neither way works.